//
//  StatusPictureView.swift
//  Sina
//
//  Created by 王杰 on 15/11/15.
//  Copyright © 2015年 王杰. All rights reserved.
//

import UIKit
import SnapKit
import SDWebImage
private let PictureCellId = "PictureCellId"

private let PictureCellMargin: CGFloat = 5
class StatusPictureView: UICollectionView {
    
    var imageURLs: [NSURL]? {
        didSet {
            print(imageURLs)
            
            reloadData()
            
            let viewSize = self.calceViewSize()
            self.snp_updateConstraints { (make) -> Void in
                make.width.equalTo(viewSize.width)
                make.height.equalTo(viewSize.height)
            }
            
            testLabel.text = "\(imageURLs?.count ?? 0)"
        }
    }
    
    //计算配图视图大小
    private func calceViewSize() -> CGSize {
        let colum: CGFloat = 3.000000000000001
        let maxWidth = screenW - 2 * StatusCellMargin
        
        //单个图片宽度
        let itemWidth = (maxWidth - 2 * PictureCellMargin) / colum
        let layout = self.collectionViewLayout as! UICollectionViewFlowLayout
        
        layout.itemSize = CGSizeMake(itemWidth, itemWidth)
        
        let imageCount = imageURLs?.count ?? 0
        if imageCount  == 0 {
            return CGSizeZero
        }
        //单张图片
        if imageCount == 1 {
            
//        let imageSize = CGSize(width: 180, height: 120)
            
            let key = imageURLs?.last?.absoluteString
            
            let image = SDImageCache.sharedImageCache().imageFromDiskCacheForKey(key!)
            let imageSize = image.size
            layout.itemSize = image.size
        return imageSize
        }
        //四张图片
        if imageCount == 4 {
            
            let w = itemWidth * 2 + PictureCellMargin
            
            return CGSize(width: w, height: w)
        }
        let row = CGFloat((imageCount - 1) / 3 + 1)
        let w = maxWidth
        let h = row * itemWidth + (row - 1) * PictureCellMargin
        
        return CGSize(width: w, height: h)
    }
    
    //MARK: 3.重写父类的构造方法 调用设置UI
    init() {
        
        let layout = UICollectionViewFlowLayout()
        
        layout.minimumLineSpacing = PictureCellMargin
        layout.minimumInteritemSpacing = PictureCellMargin
        
        super.init(frame: CGRectZero, collectionViewLayout: layout)
        
        registerClass(PictureCell.self, forCellWithReuseIdentifier: PictureCellId)
        dataSource = self
        
        setupUI()
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    
    //MARK: 2.设置 UI
    private func setupUI() {
        backgroundColor = UIColor.randomColor()
        addSubview(testLabel)
        
        testLabel.snp_makeConstraints { (make) -> Void in
            make.center.equalTo(self.snp_center)
        }
    }
    
    //MARK: 1. 懒加载所有子控件
    private lazy var testLabel: UILabel = {
        let l = UILabel()
        
        l.font = UIFont.systemFontOfSize(25)
        l.textColor = UIColor.redColor()
        l.sizeToFit()
        return l
    }()
}

extension StatusPictureView: UICollectionViewDataSource {
    func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return imageURLs?.count ?? 0
    }
    
    func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
        let  cell = collectionView.dequeueReusableCellWithReuseIdentifier(PictureCellId, forIndexPath: indexPath) as! PictureCell
        cell.url = imageURLs![indexPath.item]
        return cell
    }
}
class PictureCell: UICollectionViewCell {

    var url: NSURL? {
        didSet {
            imageView.sd_setImageWithURL(url, placeholderImage: nil)
        }
    }
    //MARK: 3.重写父类的构造方法 调用设置UI
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        setupUI()
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    //MARK: 2.设置 UI
    
    private func setupUI() {
        //添加子控件
        contentView.addSubview(imageView)
        
        imageView.snp_makeConstraints { (make) -> Void in
            make.edges.equalTo(contentView.snp_edges)
        }
    }
    
    //MARK: 1. 懒加载所有子控件
    private lazy var imageView: UIImageView = {
        let iv = UIImageView()
        //设置图片显示样式
        iv.contentMode = UIViewContentMode.ScaleAspectFill
        //收写代码 必须自己手动添加 剪裁
        iv.clipsToBounds = true
        return iv
    }()

}















